The principal activity proposed for this grant is a thorough ultrastructural study of the limbal capillary plesus and its permeability to ultrastructural tracers in rats, rabbits and primates. Initially there will be a study of the normal anatomy and movement of ultrastructural tracers in experimental animals. These studies will be followed by experimental induction of corneal vascularization produced by a variety of techniques including corneal radiofrequency burns. The new formed corneal vessels will also be examined from the viewpoint of permeability. Factors relating to stimulation or inhibition of new formed vessels will be sought.